Baxi Bermuda 50/4 behaviour questions

[andymartin86]

Hello,
I have recently moved into a house with a 50/4 inset 2 boiler and fireplace.
It works well, apart from when the boiler fires up after about 3-4 seconds it sounds like the burner pressure increases and the unit roars.
I have done a gas meter time for 2 minutes and it seems to be set around 13kw heat input so its not overgassed. I am going to buy a manometer to double check the output pressure.
My question is does the gas valve open and then change to a higher pressure after a few seconds, or should it remain at a constant pressure?
I have recently vaccumed out the combustion chamber and cleaned out the burner with mains water pressure. Everything appears spot on with the burner.
When I had the combustion chamber front off, the roaring seemed less noisy. All the flames looked good with no blocked holes etc.
One thing I have noticed is when the boiler is up to temperature (thermostat set to about 2.5) the unit fires for around a minute and then switches off for around 25secs then repeats until room stat is satisfied.
Is there any way to reduce this cycling rate or is it normal?
I know no one with a back boiler to compare with so hoping someone on here has some experience. Thanks

 

[Agile]

The site rules he preclude us giving DIY gas advice!

The obvious thing to do is to call a good gas reg engineer!

Tony

 

[andymartin86]

Fair enough about the rules.
Surely it isnt against a rule to explain how my boiler should fire up though? im only after a description of operation

 

[45yearsagasman]

You've disconnected the fire to access the boiler combustion chamber. Far to much for a DIY job. There are many checks to be done to ensure that this appliance is safe to use after your work. For your families sake, entrust it to a qualified person.

 

[jeff the gasman]

Open all gas taps until there is a medium to strong smell of gas
About 5 to 15 % gas in air. Do not ventilate the area and switch some lights on and off.
When it goes BOOOM ring 0800111999
Don't tell them I sent you.
Gordon.